latest on the shooting at a middle school in nevada. New details coming out overnight about the courageous students who rushed into the chaos. Abc's cecilia vega, is in sparks, nevada, with the latest this morning. Good morning, celia. Reporter: Students being hailed as heroes. The gunman, a boy wearing a school uniform when he opened fire here. As for why he did it, police say the motive is still unknown. As students at sparks middle school returned from fall break, shots rang out. I thought it was fake. I thought he was going to be suspended for a fake gun. He is in a school uniform. This is seen by a teacher. Reporter: One of the classmates of this reno suburb opened fire moseconds before the morning bell. Happening so fast, it was over before police arrived. The initial 911 call came, the response was less than three minutes. Reporter: The gunman shooting another student in the shoulder. Witnesses say michael landsberry, a math teacher and veteran, tried to stop the shooter, only to be shot dead himself. Then, the shooter turned the gun on himself, fatally. Did he have friends? Sort of. He got bullied a couple times. Reporter: But amid the tragedy this morning, stories of heroism. This student, part of a group that tried to help landsberry, running towards the gunfire instead of away from it. Everybody ran towards mr. Landsberry. Reporter: That's pretty brave. They didn't know how to help. They just knew they wanted to. We didn't know if he was breathing or not. Reporter: Were there teachers there helping you? The teachers ran inside. Reporter: They could still hear gunshots. So, they ran inside and hid in a dark classroom. Were you scared to be there to help him? Kind of. Reporter: Overnight, an outpouring of grief from a community in mourning. To me, that tells me that he touched somebody's heart. And that means a lot. It means a lot. Reporter: Touched a lot of people out here. Those students who ran back to help their teacher, many of them didn't know each other. Some of them had never even set foot in one of mr. Landsberry's class. They just wanted to help. School here remains closed for the rest of the week.

This transcript has been automatically generated and may not be 100% accurate.

Now Playing: Facebook suspends British-based data company used by Trump campaign

Now Playing: {{itm.title}}

{"id":20642921,"title":"Teacher Killed in Nevada School Shooting","duration":"2:30","description":"New details emerge about the victims and gunman in a middle school shooting.","url":"/GMA/video/nevada-school-shooting-teacher-killed-20642921","section":"GMA","mediaType":"default"}